My i5 750 is now running at 3.7 GHz with the help of asus auto overclocking. It was getting 11K running 4 cores on SMP
With 3 cores on SMP and an overclocked 5870 running the V16 client (client type: advanced) , I'm netting 13k: 9k from the GPU and 4K from the CPU.

I'm quite surprised that the extra 1 GHz almost doubled my PPD and almost equally surprised that taking one core out would drop my PPD by 7k PPD.

Anyways, for anyone that's interested, I used this guide to configure the V16 GPU client, though I didn't bother with WinAFC, setting affinities and priorities manually via the task manager. Make sure you set the client type to advanced like SKYMTL says here to get the best PPD from the GPU.